This section provides background information related to the present disclosure which is not necessarily prior art.
Internal combustion engines convert chemical energy of a fuel into kinetic energy through combustion of the fuel within a combustion chamber. The expansion of the combustion gasses typically causes a piston to move linearly in a cylinder of the engine. The piston is coupled to a crankshaft configured to convert the linear motion of the piston into rotation of the crankshaft, though other types of engines, such as rotary or Wankel engines for example, can convert the expansion of the combustion gasses into rotational motion without a piston. The rotational motion of the crank can be used to do work such as provide rotary power to a set of wheels of a vehicle for example, or to rotate a rotor of a generator to produce electricity for example.
Internal combustion engines that use certain fuels, such as gasoline or natural gas engines for example, typically use a spark plug to trigger ignition and combustion of an air-fuel mixture that has been compressed in the combustion chamber by the piston. A spark plug typically includes a center electrode and a ground electrode spaced apart from the center electrode by a predetermined gap. The center electrode is typically connected to an electrical source and the ground electrode is connected to a grounding source. The electrical source is typically configured to create a voltage across the gap sufficient to cause electrical arcing, i.e. a spark, to form between the center electrode and the ground electrode when the piston has compressed the air-fuel mixture in the combustion chamber. The size, location, timing, and duration of the spark are designed to ignite the air-fuel mixture to initiate combustion within the combustion chamber. Complete combustion can be important for increasing fuel efficiency and power, and decreasing emissions.
The grounding electrode of traditional spark plugs is formed from a “J” shaped conductive piece typically having a rectangular cross-section. Traditional grounding electrodes can inhibit the flow of the air-fuel mixture to the gap, which can lead to incomplete or unstable combustion. Furthermore, the combustion can cause the temperature of the typical grounding electrode to rise, which can result in premature ignition of the air-fuel mixture. The typical “J” shaped ground electrode extends and terminates freely beyond the center of the center electrode, such that the arcing does not occur at the terminal end of the “J” shape. This configuration can cause some heat to flow from the point of arcing, toward the terminal end, instead of toward the housing. This can cause heat to build up between the terminal end and the point of arcing, which can result in premature ignition of the air-fuel mixture.